[DRAFT] Comparison of WCAG 1.0 Checkpoints to WCAG 2.0, Grouped by Priorities

New WCAG 2.0 requirements not mentioned in the comparison tables below

New Level A requirements

1.3.3 Sensory Characteristics: Instructions provided for understanding and operating content do not rely solely on sensory characteristics of components such as shape, size, visual location, orientation, or sound. (Level A) How to Meet 1.3.3 Understanding 1.3.3

Note: For requirements related to color, refer to Guideline 1.4.

1.4.2 Audio Control: If any audio on a Web page plays automatically for more than 3 seconds, either a mechanism is available to pause or stop the audio, or a mechanism is available to control audio volume independently from the overall system volume level. (Level A) How to Meet 1.4.2 Understanding 1.4.2

Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether or not it is used to meet other success criteria) must meet this success criterion. See Conformance Requirement 5: Non-Interference.

2.1.2 No Keyboard Trap: If keyboard focus can be moved to a component of the page using a keyboard interface, then focus can be moved away from that component using only a keyboard interface, and, if it requires more than unmodified arrow or tab keys, the user is advised of the method for moving focus away. (Level A) How to Meet 2.1.2 Understanding 2.1.2

Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.

2.4.2 Page Titled: Web pages have titles that describe topic or purpose. (Level A) How to Meet 2.4.2 Understanding 2.4.2

3.3.1 Error Identification: If an input error is automatically detected, the item that is in error is identified and the error is described to the user in text. (Level A) How to Meet 3.3.1 Understanding 3.3.1

3.3.2 Labels or Instructions: Labels or instructions are provided when content requires user input. (Level A) How to Meet 3.3.2 Understanding 3.3.2

New Level AA requirements

2.4.6 Headings and Labels: Headings and labels describe topic or purpose. (Level AA) How to Meet 2.4.6 Understanding 2.4.6

3.3.3 Error Suggestion: If an input error is automatically detected and suggestions for correction are known, then the suggestions are provided to the user, unless it would jeopardize the security or purpose of the content. (Level AA) How to Meet 3.3.3 Understanding 3.3.3

3.3.4 Error Prevention (Legal, Financial, Data): For Web pages that cause legal commitments or financial transactions for the user to occur, that modify or delete user-controllable data in data storage systems, or that submit user test responses, at least one of the following is true: (Level AA) How to Meet 3.3.4 Understanding 3.3.4

Reversible: Submissions are reversible.
Checked: Data entered by the user is checked for input errors and the user is provided an opportunity to correct them.
Confirmed: A mechanism is available for reviewing, confirming, and correcting information before finalizing the submission.

New Level AAA requirements

1.2.6 Sign Language: Sign language interpretation is provided for all prerecorded audio content in synchronized media. (Level AAA) How to Meet 1.2.6 Understanding 1.2.6

1.2.8 Full Text Alternative: A full text alternative for synchronized media including any interaction is provided for all prerecorded synchronized media and a text alternative that presents equivalent information is provided for all prerecorded video-only media. (Level AAA) How to Meet 1.2.8 Understanding 1.2.8

1.4.7 Low or No Background Audio: For audio content that (1) is not an audio CAPTCHA and (2) contains speech in the foreground, at least one of the following is true: (Level AAA) How to Meet 1.4.7 Understanding 1.4.7

No Background: The audio does not contain background sounds.
Turn Off: The background sounds can be turned off.
20 dB: The background sounds are at least 20 decibels lower than the foreground speech content, with the exception of occasional sound effects.
Note: Per the definition of "decibel," background sound that meets this requirement will be approximately four times quieter than the foreground speech content.

1.4.8 Visual Presentation: For the visual presentation of blocks of text, a mechanism is available to achieve the following: (Level AAA) How to Meet 1.4.8 Understanding 1.4.8

foreground and background colors can be selected by the user
width is no more than 80 characters or glyphs (40 if CJK)
text is not justified (aligned to both the left and the right margins)
line spacing (leading) is at least space-and-a-half within paragraphs, and paragraph spacing is at least 1.5 times larger than the line spacing
text is resized without assistive technology up to 200 percent in a way that does not require the user to scroll horizontally to read a line of text on a full-screen window

2.2.3 No Timing: Timing is not an essential part of the event or activity presented by the content, except for non-interactive synchronized media and real-time events. (Level AAA) How to Meet 2.2.3 Understanding 2.2.3

2.2.5 Re-authenticating: When an authenticated session expires, the user can continue the activity without loss of data after re-authenticating. (Level AAA) How to Meet 2.2.5 Understanding 2.2.5

2.4.7 Focus Visible: Any keyboard operable user interface has a mode of operation where the keyboard focus indicator is visible. (Level AA) How to Meet 2.4.7 Understanding 2.4.7

2.4.8 Location: Information about the user's location within a set of Web pages is available. (Level AAA) How to Meet 2.4.8 Understanding 2.4.8

3.1.3 Unusual Words: A mechanism is available for identifying specific definitions of words or phrases used in an unusual or restricted way, including idioms and jargon. (Level AAA) How to Meet 3.1.3 Understanding 3.1.3

3.1.6 Pronunciation: A mechanism is available for identifying specific pronunciation of words where meaning of the words, in context, is ambiguous without knowing the pronunciation. (Level AAA) How to Meet 3.1.6 Understanding 3.1.6

3.3.5 Help: Context-sensitive help is available. (Level AAA) How to Meet 3.3.5 Understanding 3.3.5

3.3.6 Error Prevention (All): For Web pages that require the user to submit information, at least one of the following is true: (Level AAA) How to Meet 3.3.6 Understanding 3.3.6

Reversible: Submissions are reversible.
Checked: Data entered by the user is checked for input errors and the user is provided an opportunity to correct them.
Confirmed: A mechanism is available for reviewing, confirming, and correcting information before finalizing the submission.

WCAG 1.0 Priority 1 checkpoints

In General (Priority 1)	WCAG 2.0
1.1: Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ascii art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]	1.1.1 Non-text Content: All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for the situations listed below. (Level A) How to Meet 1.1.1 Understanding 1.1.1 Controls, Input: If non-text content is a control or accepts user input, then it has a name that describes its purpose. (Refer to Guideline 4.1 for additional requirements for controls and content that accepts user input.) Time-Based Media: If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content. (Refer to Guideline 1.2 for additional requirements for media.) Test: If non-text content is a test or exercise that must be presented in non-text format, then text alternatives at least provide descriptive identification of the non-text content. Sensory: If non-text content is primarily intended to create a specific sensory experience, then text alternatives at least provide descriptive identification of the non-text content. CAPTCHA: If the purpose non-text content is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided, and alternative forms of CAPTCHA using output modes for different types of sensory perception are provided to accommodate different disabilities. Decoration, Formatting, Invisible: If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it is implemented in a way that it can be ignored by assistive technology. 1.2.1 Audio-only and Video-only (Prerecorded): For prerecorded audio-only and prerecorded video-only media, the following are true, except when the audio or video is a media alternative for text and is clearly labeled as such: (Level A) How to Meet 1.2.1 Understanding 1.2.1 Prerecorded Audio-only: A text alternative is provided that presents equivalent information for prerecorded audio-only content. Prerecorded Video-only: Either a text alternative or an audio track is provided that presents equivalent information for prerecorded video-only content. 1.2.9 Live Audio-only: A text alternative that presents equivalent information for live audio-only content is provided. (Level AAA) How to Meet 1.2.9 Understanding 1.2.9 Additional Notes: For some types of non-text content, it may be necessary to provide a conforming alternate version. Refer to conformance requirement 1 and conformance requirement 4 for more information. Images used as bullets are also covered in Guideline 1.3 with regard to CSS usage. For framesets, `noframes` is no longer required. For multimedia, alternatives (beyond labels) are covered under Guideline 1.2. ASCII art is non-text content.
2.1: Ensure that all information conveyed with color is also available without color, for example from context or markup. [Priority 1]	1.4.1 Use of Color: Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. (Level A) How to Meet 1.4.1 Understanding 1.4.1 Note: This success criterion addresses color perception specifically. Other forms of perception are covered in Guideline 1.3 including programmatic access to color and other visual presentation coding.
4.1: Clearly identify changes in the natural language of a document's text and any text equivalents (e.g., captions). [Priority 1]	3.1.2 Language of Parts: The human language of each passage or phrase in the content can be programmatically determined except for proper names, technical terms, words of indeterminate language, and words or phrases that have become part of the vernacular of the immediately surrounding text. (Level AA) How to Meet 3.1.2 Understanding 3.1.2
6.1: Organize documents so they may be read without style sheets. For example, when an HTML document is rendered without associated style sheets, it must still be possible to read the document. [Priority 1]	Conformance Requirement 4: Accessibility-Supported Technologies Only: Only accessibility supported technologies are relied upon to satisfy the success criteria. Any information or functionality that is implemented in technologies that are not accessibility supported are also be available via technologies that are accessibility supported. (See Understanding accessibility support.) Understanding Conformance Requirement 4 Conformance Requirement 5: Non-Interference: If technologies that are not accessibility supported are used on a page, or accessibility-supported technologies are used in a non-conforming way, then they do not block the ability of users to access the rest of the page. In addition, the Web page as a whole continues to meet the conformance requirements under all of the following conditions: Understanding Conformance Requirement 5 when any technology that is not accessibility-supported is turned on in a user agent, and when it is turned off in a user agent, and when it is not supported by a user agent Note: The following success criteria all apply to full pages including technologies that are not accessibility supported or relied upon to meet the other success criteria because they deal with things that could interfere with overall use of the page: 1.4.2 - Audio Control, 2.1.2 - No Keyboard Trap, 2.3.1 - Three Flashes or Below Threshold, and 2.2.2 - Pause, Stop, Hide.
6.2: Ensure that equivalents for dynamic content are updated when the dynamic content changes. [Priority 1]	F20: Failure of Success Criterion 1.1.1 and 4.1.2 due to not updating text alternatives when changes to non-text content occur Additional Notes: Text alternatives are addressed in Guideline 1.1, 1.2 and 4.1. If providing a conforming alternate version, then it is as up to date as the non-conforming content, (see conformance requirement 1 and conforming alternate version).
7.1: Until user agents allow users to control flickering, avoid causing the screen to flicker. [Priority 1]	2.3.1 Three Flashes or Below Threshold: Web pages do not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds. (Level A) How to Meet 2.3.1 Understanding 2.3.1 Note: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference. 2.3.2 Three Flashes: Web pages do not contain anything that flashes more than three times in any one second period. (Level AAA) How to Meet 2.3.2 Understanding 2.3.2
14.1: Use the clearest and simplest language appropriate for a site's content. [Priority 1]	Some of the Level AAA success criteria in Guideline 3.1 as well as the Advisory Techniques for Guideline 3.1 aid in making content more understandable. There is no direct mapping.
4.1: Clearly identify changes in the natural language of a document's text and any text equivalents (e.g., captions). [Priority 1]	3.1.2 Language of Parts: The human language of each passage or phrase in the content can be programmatically determined except for proper names, technical terms, words of indeterminate language, and words or phrases that have become part of the vernacular of the immediately surrounding text. (Level AA) How to Meet 3.1.2 Understanding 3.1.2
And if you use images and image maps (Priority 1)	WCAG 2.0
1.2: Provide redundant text links for each active region of a server-side image map. [Priority 1]	With regard to text alternatives: 1.1.1 Non-text Content: All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for the situations listed below. (Level A) How to Meet 1.1.1 Understanding 1.1.1 Controls, Input: If non-text content is a control or accepts user input, then it has a name that describes its purpose. (Refer to Guideline 4.1 for additional requirements for controls and content that accepts user input.) Time-Based Media: If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content. (Refer to Guideline 1.2 for additional requirements for media.) Test: If non-text content is a test or exercise that must be presented in non-text format, then text alternatives at least provide descriptive identification of the non-text content. Sensory: If non-text content is primarily intended to create a specific sensory experience, then text alternatives at least provide descriptive identification of the non-text content. CAPTCHA: If the purpose non-text content is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided, and alternative forms of CAPTCHA using output modes for different types of sensory perception are provided to accommodate different disabilities. Decoration, Formatting, Invisible: If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it is implemented in a way that it can be ignored by assistive technology. With regard to keyboard access: 2.1.1 Keyboard: All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints. (Level A) How to Meet 2.1.1 Understanding 2.1.1 Note 1: This exception relates to the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path dependent input but the underlying function (text input) does not. Note 2: This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation. 2.4.4 Link Purpose (In Context): The purpose of each link can be determined from the link text alone, or from the link text together with its programmatically determined link context, except where the purpose of the link would be ambiguous to users in general. (Level A) How to Meet 2.4.4 Understanding 2.4.4 Additional Notes: Server-side image maps are not keyboard accessible.
9.1: Provide client-side image maps instead of server-side image maps except where the regions cannot be defined with an available geometric shape. [Priority 1]	With regard to text alternatives: 1.1.1 Non-text Content: All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for the situations listed below. (Level A) How to Meet 1.1.1 Understanding 1.1.1 Controls, Input: If non-text content is a control or accepts user input, then it has a name that describes its purpose. (Refer to Guideline 4.1 for additional requirements for controls and content that accepts user input.) Time-Based Media: If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content. (Refer to Guideline 1.2 for additional requirements for media.) Test: If non-text content is a test or exercise that must be presented in non-text format, then text alternatives at least provide descriptive identification of the non-text content. Sensory: If non-text content is primarily intended to create a specific sensory experience, then text alternatives at least provide descriptive identification of the non-text content. CAPTCHA: If the purpose non-text content is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided, and alternative forms of CAPTCHA using output modes for different types of sensory perception are provided to accommodate different disabilities. Decoration, Formatting, Invisible: If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it is implemented in a way that it can be ignored by assistive technology. With regard to keyboard access: 2.1.1 Keyboard: All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints. (Level A) How to Meet 2.1.1 Understanding 2.1.1 Note 1: This exception relates to the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path dependent input but the underlying function (text input) does not. Note 2: This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation. Additional Notes: Server-side image maps are not keyboard accessible.
And if you use tables (Priority 1)	WCAG 2.0
5.1: For data tables, identify row and column headers. [Priority 1]	1.3.1 Info and Relationships: Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A) How to Meet 1.3.1 Understanding 1.3.1 Specifically: H51: Using table markup to present tabular information H63: Using the scope attribute to associate header cells and data cells in data tables
5.2: For data tables that have two or more logical levels of row or column headers, use markup to associate data cells and header cells. [Priority 1]	1.3.1 Info and Relationships: Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A) How to Meet 1.3.1 Understanding 1.3.1 Specifically: H43: Using id and headers attributes to associate data cells with header cells in data tables
And if you use frames (Priority 1)	WCAG 2.0
12.1: Title each frame to facilitate frame identification and navigation. [Priority 1]	2.4.1 Bypass Blocks: A mechanism is available to bypass blocks of content that are repeated on multiple Web pages. (Level A) How to Meet 2.4.1 Understanding 2.4.1 4.1.2 Name, Role, Value: For all user user interface components (including but not limited to: form elements, links and components generated by scripts), the name and role can be programmatically determined; states, properties, and values that can be set by the user can be programmatically set; and notification of changes to these items is available to user agents, including assistive technologies. (Level A) How to Meet 4.1.2 Understanding 4.1.2 Note: This success criterion is primarily for Web authors who develop or script their own user interface components. For example, standard HTML controls already meet this success criterion when used according to specification. Additional Notes: This checkpoint partially maps to Success Criterion 2.4.2 (Level A).
And if you use applets and scripts (Priority 1)	WCAG 2.0
6.3: Ensure that pages are usable when scripts, applets, or other programmatic objects are turned off or not supported. If this is not possible, provide equivalent information on an alternative accessible page. [Priority 1]	Conformance Requirement 1: Conformance Level: One of the following levels of conformance is met in full. Understanding Conformance Requirement 1 Level A: For Level A conformance (the minimum level of conformance), the Web page satisfies all the Level A Success Criteria, or a conforming alternate version is provided. Level AA: For Level AA conformance, the Web page satisfies all the Level A and Level AA Success Criteria, or a Level AA conforming alternate version is provided. Level AAA: For Level AAA conformance, the Web page satisfies all the Level A, Level AA and Level AAA Success Criteria, or a Level AAA conforming alternate version is provided. Note 1: Although conformance can only be achieved at the stated levels, authors are encouraged to satisfy and report progress toward meeting success criteria from all levels beyond the achieved level of conformance. Note 2: It is not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA Success Criteria for some content. Conformance Requirement 4: Accessibility-Supported Technologies Only: Only accessibility supported technologies are relied upon to satisfy the success criteria. Any information or functionality that is implemented in technologies that are not accessibility supported are also be available via technologies that are accessibility supported. (See Understanding accessibility support.) Understanding Conformance Requirement 4 Conformance Requirement 5: Non-Interference: If technologies that are not accessibility supported are used on a page, or accessibility-supported technologies are used in a non-conforming way, then they do not block the ability of users to access the rest of the page. In addition, the Web page as a whole continues to meet the conformance requirements under all of the following conditions: Understanding Conformance Requirement 5 when any technology that is not accessibility-supported is turned on in a user agent, and when it is turned off in a user agent, and when it is not supported by a user agent Note: The following success criteria all apply to full pages including technologies that are not accessibility supported or relied upon to meet the other success criteria because they deal with things that could interfere with overall use of the page: 1.4.2 - Audio Control, 2.1.2 - No Keyboard Trap, 2.3.1 - Three Flashes or Below Threshold, and 2.2.2 - Pause, Stop, Hide. Additional Notes: There is no longer a requirement that pages work without script or other programmatic objects, only that those objects meet the conformance requirements listed above.
And if you use multimedia (Priority 1)	WCAG 2.0
1.3: Until user agents can automatically read aloud the text equivalent of a visual track, provide an auditory description of the important information of the visual track of a multimedia presentation. [Priority 1]	1.2.3 Audio Description or Full Text Alternative: A full text alternative for synchronized media including any interaction or audio description of the prerecorded video content is provided for synchronized media, except when the media is a media alternative for text and is clearly labeled as such. (Level A) How to Meet 1.2.3 Understanding 1.2.3 1.2.5 Audio Description: Audio description is provided for all prerecorded video content in synchronized media. (Level AA) How to Meet 1.2.5 Understanding 1.2.5 1.2.7 Audio Description (Extended): Extended audio description is provided for all prerecorded video content in synchronized media. (Level AAA) How to Meet 1.2.7 Understanding 1.2.7
1.4: For any time-based multimedia presentation (e.g., a movie or animation), synchronize equivalent alternatives (e.g., captions or auditory descriptions of the visual track) with the presentation. [Priority 1]	1.2.2 Captions (Prerecorded): Captions are provided for all prerecorded audio content in synchronized media, except when the media is a media alternative for text and is clearly labeled as such. (Level A) How to Meet 1.2.2 Understanding 1.2.2 1.2.3 Audio Description or Full Text Alternative: A full text alternative for synchronized media including any interaction or audio description of the prerecorded video content is provided for synchronized media, except when the media is a media alternative for text and is clearly labeled as such. (Level A) How to Meet 1.2.3 Understanding 1.2.3 1.2.4 Captions (Live): Captions are provided for all live audio content in synchronized media. (Level AA) How to Meet 1.2.4 Understanding 1.2.4 1.2.5 Audio Description: Audio description is provided for all prerecorded video content in synchronized media. (Level AA) How to Meet 1.2.5 Understanding 1.2.5 1.2.7 Audio Description (Extended): Extended audio description is provided for all prerecorded video content in synchronized media. (Level AAA) How to Meet 1.2.7 Understanding 1.2.7
And if all else fails (Priority 1)	WCAG 2.0
11.4: If, after best efforts, you cannot create an accessible page, provide a link to an alternative page that uses W3C technologies, is accessible, has equivalent information (or functionality), and is updated as often as the inaccessible (original) page. [Priority 1]	Conformance Requirement 1: Conformance Level: One of the following levels of conformance is met in full. Understanding Conformance Requirement 1 Level A: For Level A conformance (the minimum level of conformance), the Web page satisfies all the Level A Success Criteria, or a conforming alternate version is provided. Level AA: For Level AA conformance, the Web page satisfies all the Level A and Level AA Success Criteria, or a Level AA conforming alternate version is provided. Level AAA: For Level AAA conformance, the Web page satisfies all the Level A, Level AA and Level AAA Success Criteria, or a Level AAA conforming alternate version is provided. Note 1: Although conformance can only be achieved at the stated levels, authors are encouraged to satisfy and report progress toward meeting success criteria from all levels beyond the achieved level of conformance. Note 2: It is not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA Success Criteria for some content.

In General (Priority 1)

WCAG 2.0

1.1: Provide a text equivalent for every non-text element (e.g., via "alt", "longdesc", or in element content). This includes: images, graphical representations of text (including symbols), image map regions, animations (e.g., animated GIFs), applets and programmatic objects, ascii art, frames, scripts, images used as list bullets, spacers, graphical buttons, sounds (played with or without user interaction), stand-alone audio files, audio tracks of video, and video. [Priority 1]

1.1.1 Non-text Content: All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for the situations listed below. (Level A) How to Meet 1.1.1 Understanding 1.1.1

Controls, Input: If non-text content is a control or accepts user input, then it has a name that describes its purpose. (Refer to Guideline 4.1 for additional requirements for controls and content that accepts user input.)
Time-Based Media: If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content. (Refer to Guideline 1.2 for additional requirements for media.)
Test: If non-text content is a test or exercise that must be presented in non-text format, then text alternatives at least provide descriptive identification of the non-text content.
Sensory: If non-text content is primarily intended to create a specific sensory experience, then text alternatives at least provide descriptive identification of the non-text content.
CAPTCHA: If the purpose non-text content is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided, and alternative forms of CAPTCHA using output modes for different types of sensory perception are provided to accommodate different disabilities.
Decoration, Formatting, Invisible: If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it is implemented in a way that it can be ignored by assistive technology.

1.2.1 Audio-only and Video-only (Prerecorded): For prerecorded audio-only and prerecorded video-only media, the following are true, except when the audio or video is a media alternative for text and is clearly labeled as such: (Level A) How to Meet 1.2.1 Understanding 1.2.1

Prerecorded Audio-only: A text alternative is provided that presents equivalent information for prerecorded audio-only content.
Prerecorded Video-only: Either a text alternative or an audio track is provided that presents equivalent information for prerecorded video-only content.

1.2.9 Live Audio-only: A text alternative that presents equivalent information for live audio-only content is provided. (Level AAA) How to Meet 1.2.9 Understanding 1.2.9

Additional Notes:

For some types of non-text content, it may be necessary to provide a conforming alternate version. Refer to conformance requirement 1 and conformance requirement 4 for more information.
Images used as bullets are also covered in Guideline 1.3 with regard to CSS usage.
For framesets, noframes is no longer required.
For multimedia, alternatives (beyond labels) are covered under Guideline 1.2.
ASCII art is non-text content.

2.1: Ensure that all information conveyed with color is also available without color, for example from context or markup. [Priority 1]

1.4.1 Use of Color: Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element. (Level A) How to Meet 1.4.1 Understanding 1.4.1

Note: This success criterion addresses color perception specifically. Other forms of perception are covered in Guideline 1.3 including programmatic access to color and other visual presentation coding.

4.1: Clearly identify changes in the natural language of a document's text and any text equivalents (e.g., captions). [Priority 1]

3.1.2 Language of Parts: The human language of each passage or phrase in the content can be programmatically determined except for proper names, technical terms, words of indeterminate language, and words or phrases that have become part of the vernacular of the immediately surrounding text. (Level AA) How to Meet 3.1.2 Understanding 3.1.2

6.1: Organize documents so they may be read without style sheets. For example, when an HTML document is rendered without associated style sheets, it must still be possible to read the document. [Priority 1]

Conformance Requirement 4: Accessibility-Supported Technologies Only: Only accessibility supported technologies are relied upon to satisfy the success criteria. Any information or functionality that is implemented in technologies that are not accessibility supported are also be available via technologies that are accessibility supported. (See Understanding accessibility support.) Understanding Conformance Requirement 4

Conformance Requirement 5: Non-Interference: If technologies that are not accessibility supported are used on a page, or accessibility-supported technologies are used in a non-conforming way, then they do not block the ability of users to access the rest of the page. In addition, the Web page as a whole continues to meet the conformance requirements under all of the following conditions: Understanding Conformance Requirement 5

when any technology that is not accessibility-supported is turned on in a user agent, and
when it is turned off in a user agent, and
when it is not supported by a user agent

Note: The following success criteria all apply to full pages including technologies that are not accessibility supported or relied upon to meet the other success criteria because they deal with things that could interfere with overall use of the page: 1.4.2 - Audio Control, 2.1.2 - No Keyboard Trap, 2.3.1 - Three Flashes or Below Threshold, and 2.2.2 - Pause, Stop, Hide.

6.2: Ensure that equivalents for dynamic content are updated when the dynamic content changes. [Priority 1]

F20: Failure of Success Criterion 1.1.1 and 4.1.2 due to not updating text alternatives when changes to non-text content occur

Additional Notes:

Text alternatives are addressed in Guideline 1.1, 1.2 and 4.1.
If providing a conforming alternate version, then it is as up to date as the non-conforming content, (see conformance requirement 1 and conforming alternate version).

7.1: Until user agents allow users to control flickering, avoid causing the screen to flicker. [Priority 1]

2.3.1 Three Flashes or Below Threshold: Web pages do not contain anything that flashes more than three times in any one second period, or the flash is below the general flash and red flash thresholds. (Level A) How to Meet 2.3.1 Understanding 2.3.1

2.3.2 Three Flashes: Web pages do not contain anything that flashes more than three times in any one second period. (Level AAA) How to Meet 2.3.2 Understanding 2.3.2

14.1: Use the clearest and simplest language appropriate for a site's content. [Priority 1]

Some of the Level AAA success criteria in Guideline 3.1 as well as the Advisory Techniques for Guideline 3.1 aid in making content more understandable. There is no direct mapping.

4.1: Clearly identify changes in the natural language of a document's text and any text equivalents (e.g., captions). [Priority 1]

And if you use images and image maps (Priority 1)

WCAG 2.0

1.2: Provide redundant text links for each active region of a server-side image map. [Priority 1]

With regard to text alternatives:

Controls, Input: If non-text content is a control or accepts user input, then it has a name that describes its purpose. (Refer to Guideline 4.1 for additional requirements for controls and content that accepts user input.)
Time-Based Media: If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content. (Refer to Guideline 1.2 for additional requirements for media.)
Test: If non-text content is a test or exercise that must be presented in non-text format, then text alternatives at least provide descriptive identification of the non-text content.
Sensory: If non-text content is primarily intended to create a specific sensory experience, then text alternatives at least provide descriptive identification of the non-text content.
CAPTCHA: If the purpose non-text content is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided, and alternative forms of CAPTCHA using output modes for different types of sensory perception are provided to accommodate different disabilities.
Decoration, Formatting, Invisible: If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it is implemented in a way that it can be ignored by assistive technology.

With regard to keyboard access:

2.1.1 Keyboard: All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints. (Level A) How to Meet 2.1.1 Understanding 2.1.1

Note 1: This exception relates to the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path dependent input but the underlying function (text input) does not.

Note 2: This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation.

2.4.4 Link Purpose (In Context): The purpose of each link can be determined from the link text alone, or from the link text together with its programmatically determined link context, except where the purpose of the link would be ambiguous to users in general. (Level A) How to Meet 2.4.4 Understanding 2.4.4

Additional Notes:

Server-side image maps are not keyboard accessible.

9.1: Provide client-side image maps instead of server-side image maps except where the regions cannot be defined with an available geometric shape. [Priority 1]

With regard to text alternatives:

Controls, Input: If non-text content is a control or accepts user input, then it has a name that describes its purpose. (Refer to Guideline 4.1 for additional requirements for controls and content that accepts user input.)
Time-Based Media: If non-text content is time-based media, then text alternatives at least provide descriptive identification of the non-text content. (Refer to Guideline 1.2 for additional requirements for media.)
Test: If non-text content is a test or exercise that must be presented in non-text format, then text alternatives at least provide descriptive identification of the non-text content.
Sensory: If non-text content is primarily intended to create a specific sensory experience, then text alternatives at least provide descriptive identification of the non-text content.
CAPTCHA: If the purpose non-text content is to confirm that content is being accessed by a person rather than a computer, then text alternatives that identify and describe the purpose of the non-text content are provided, and alternative forms of CAPTCHA using output modes for different types of sensory perception are provided to accommodate different disabilities.
Decoration, Formatting, Invisible: If non-text content is pure decoration, is used only for visual formatting, or is not presented to users, then it is implemented in a way that it can be ignored by assistive technology.

With regard to keyboard access:

Note 2: This does not forbid and should not discourage providing mouse input or other input methods in addition to keyboard operation.

Additional Notes:

Server-side image maps are not keyboard accessible.

And if you use tables (Priority 1)

WCAG 2.0

5.1: For data tables, identify row and column headers. [Priority 1]

1.3.1 Info and Relationships: Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A) How to Meet 1.3.1 Understanding 1.3.1

Specifically:

5.2: For data tables that have two or more logical levels of row or column headers, use markup to associate data cells and header cells. [Priority 1]

Specifically:

H43: Using id and headers attributes to associate data cells with header cells in data tables

And if you use frames (Priority 1)

WCAG 2.0

12.1: Title each frame to facilitate frame identification and navigation. [Priority 1]

2.4.1 Bypass Blocks: A mechanism is available to bypass blocks of content that are repeated on multiple Web pages. (Level A) How to Meet 2.4.1 Understanding 2.4.1

4.1.2 Name, Role, Value: For all user user interface components (including but not limited to: form elements, links and components generated by scripts), the name and role can be programmatically determined; states, properties, and values that can be set by the user can be programmatically set; and notification of changes to these items is available to user agents, including assistive technologies. (Level A) How to Meet 4.1.2 Understanding 4.1.2

Note: This success criterion is primarily for Web authors who develop or script their own user interface components. For example, standard HTML controls already meet this success criterion when used according to specification.

Additional Notes:

This checkpoint partially maps to Success Criterion 2.4.2 (Level A).

And if you use applets and scripts (Priority 1)

WCAG 2.0

6.3: Ensure that pages are usable when scripts, applets, or other programmatic objects are turned off or not supported. If this is not possible, provide equivalent information on an alternative accessible page. [Priority 1]

Conformance Requirement 1: Conformance Level: One of the following levels of conformance is met in full. Understanding Conformance Requirement 1

Level A: For Level A conformance (the minimum level of conformance), the Web page satisfies all the Level A Success Criteria, or a conforming alternate version is provided.
Level AA: For Level AA conformance, the Web page satisfies all the Level A and Level AA Success Criteria, or a Level AA conforming alternate version is provided.
Level AAA: For Level AAA conformance, the Web page satisfies all the Level A, Level AA and Level AAA Success Criteria, or a Level AAA conforming alternate version is provided.

Note 1: Although conformance can only be achieved at the stated levels, authors are encouraged to satisfy and report progress toward meeting success criteria from all levels beyond the achieved level of conformance.

Note 2: It is not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA Success Criteria for some content.

when any technology that is not accessibility-supported is turned on in a user agent, and
when it is turned off in a user agent, and
when it is not supported by a user agent

Additional Notes:

There is no longer a requirement that pages work without script or other programmatic objects, only that those objects meet the conformance requirements listed above.

And if you use multimedia (Priority 1)

WCAG 2.0

1.3: Until user agents can automatically read aloud the text equivalent of a visual track, provide an auditory description of the important information of the visual track of a multimedia presentation. [Priority 1]

1.2.3 Audio Description or Full Text Alternative: A full text alternative for synchronized media including any interaction or audio description of the prerecorded video content is provided for synchronized media, except when the media is a media alternative for text and is clearly labeled as such. (Level A) How to Meet 1.2.3 Understanding 1.2.3

1.2.5 Audio Description: Audio description is provided for all prerecorded video content in synchronized media. (Level AA) How to Meet 1.2.5 Understanding 1.2.5

1.2.7 Audio Description (Extended): Extended audio description is provided for all prerecorded video content in synchronized media. (Level AAA) How to Meet 1.2.7 Understanding 1.2.7

1.4: For any time-based multimedia presentation (e.g., a movie or animation), synchronize equivalent alternatives (e.g., captions or auditory descriptions of the visual track) with the presentation. [Priority 1]

1.2.2 Captions (Prerecorded): Captions are provided for all prerecorded audio content in synchronized media, except when the media is a media alternative for text and is clearly labeled as such. (Level A) How to Meet 1.2.2 Understanding 1.2.2

1.2.4 Captions (Live): Captions are provided for all live audio content in synchronized media. (Level AA) How to Meet 1.2.4 Understanding 1.2.4

1.2.5 Audio Description: Audio description is provided for all prerecorded video content in synchronized media. (Level AA) How to Meet 1.2.5 Understanding 1.2.5

1.2.7 Audio Description (Extended): Extended audio description is provided for all prerecorded video content in synchronized media. (Level AAA) How to Meet 1.2.7 Understanding 1.2.7

And if all else fails (Priority 1)

WCAG 2.0

11.4: If, after best efforts, you cannot create an accessible page, provide a link to an alternative page that uses W3C technologies, is accessible, has equivalent information (or functionality), and is updated as often as the inaccessible (original) page. [Priority 1]

Conformance Requirement 1: Conformance Level: One of the following levels of conformance is met in full. Understanding Conformance Requirement 1

Level A: For Level A conformance (the minimum level of conformance), the Web page satisfies all the Level A Success Criteria, or a conforming alternate version is provided.
Level AA: For Level AA conformance, the Web page satisfies all the Level A and Level AA Success Criteria, or a Level AA conforming alternate version is provided.
Level AAA: For Level AAA conformance, the Web page satisfies all the Level A, Level AA and Level AAA Success Criteria, or a Level AAA conforming alternate version is provided.

Note 2: It is not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA Success Criteria for some content.

WCAG 1.0 Priority 2 checkpoints

In General (Priority 2)	WCAG 2.0
2.2: Ensure that foreground and background color combinations provide sufficient contrast when viewed by someone having color deficits or when viewed on a black and white screen. [Priority 2 for images, Priority 3 for text].	1.4.3 Contrast (Minimum): The visual presentation of text and images of text has a contrast ratio of at least 5:1, except for the following: (Level AA) How to Meet 1.4.3 Understanding 1.4.3 Large Print: Large-scale text and images of large-scale text have a contrast ratio of at least 3:1; Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are incidental text in an image, or that are not visible to anyone, have no minimum contrast requirement. Logotypes: Text that is part of a logo or brand name has no minimum contrast requirement. 1.4.6 Contrast (Enhanced): The visual presentation of text and images of text has a contrast ratio of at least 7:1, except for the following: (Level AAA) How to Meet 1.4.6 Understanding 1.4.6 Large Print: Large-scale text and images of large-scale text have a contrast ratio of at least 5:1; Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are incidental text in an image, or that are not visible to anyone, have no minimum contrast requirement. Logotypes: Text that is part of a logo or brand name has no minimum contrast requirement.
3.1: When an appropriate markup language exists, use markup rather than images to convey information. [Priority 2]	1.4.5 Images of Text: If the technologies being used can achieve the visual presentation, text is used to convey information rather than images of text except for the following: (Level AA) How to Meet 1.4.5 Understanding 1.4.5 Customizable: The image of text can be visually customized to the user's requirements; Essential: A particular presentation of text is essential to the information being conveyed. Note: Logotypes (text that is part of a logo or brand name) are considered essential. 1.4.9 Images of Text (No Exception): Images of text are only used for pure decoration or where a particular presentation of text is essential to the information being conveyed. (Level AAA) How to Meet 1.4.9 Understanding 1.4.9 Note: Logotypes (text that is part of a logo or brand name) are considered essential. Conformance Requirement 4: Accessibility-Supported Technologies Only: Only accessibility supported technologies are relied upon to satisfy the success criteria. Any information or functionality that is implemented in technologies that are not accessibility supported are also be available via technologies that are accessibility supported. (See Understanding accessibility support.) Understanding Conformance Requirement 4
3.2: Create documents that validate to published formal grammars. [Priority 2]	4.1.1 Parsing: In content implemented using markup languages, elements have complete start and end tags, elements are nested according to their specifications, elements do not contain duplicate attributes, and any IDs are unique, except where the specifications allow these features. (Level A) How to Meet 4.1.1 Understanding 4.1.1 Note: Start and end tags that are missing a critical character in their formation, such as a closing angle bracket or a mismatched attribute value quotation mark are not complete. Additional Notes: Validating to published formal grammars is a stronger requirement than what is required by Success Criterion 4.1.1 but validation is one of the sufficient techniques for this Success Criterion. Refer to Understanding Success Criterion 4.1.1
3.3: Use style sheets to control layout and presentation. [Priority 2]	This checkpoint maps to several sufficient and advisory techniques related to Success Criterion 1.3.1 (Level A), Success Criterion 1.3.2 (Level A), Success Criterion 1.4.1 (Level A), Success Criterion 1.4.4 (Level AA), Success Criterion 1.4.5 (Level AA), Success Criterion 2.4.7 (Level AA), Success Criterion 1.4.8 (Level AAA), and Success Criterion 1.4.9 (Level AAA). There is no direct mapping.
3.4: Use relative rather than absolute units in markup language attribute values and style sheet property values. [Priority 2]	1.4.4 Resize text: Text (but not images of text) can be resized without assistive technology up to 200 percent without loss of content or functionality. (Level AA) How to Meet 1.4.4 Understanding 1.4.4 Additional Notes: Some aspects of Success Criterion 1.4.8 (Level AAA) also relate to this checkpoint.
3.5 Use header elements to convey document structure and use them according to specification. [Priority 2]	1.3.1 Info and Relationships: Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A) How to Meet 1.3.1 Understanding 1.3.1 2.4.10 Section Headings: Section headings are used to organize the content. (Level AAA) How to Meet 2.4.10 Understanding 2.4.10 Note 1: "Heading" is used in its general sense and includes titles and other ways to add a heading to different types of content. Note 2: This success criterion covers sections within writing, not user interface components. User Interface components are covered under Success Criterion 4.1.2.
3.6: Mark up lists and list items properly. [Priority 2]	1.3.1 Info and Relationships: Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A) How to Meet 1.3.1 Understanding 1.3.1 Specifically: H48: Using ol, ul and dl for lists
3.7: Mark up quotations. Do not use quotation markup for formatting effects such as indentation. [Priority 2]	1.3.1 Info and Relationships: Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A) How to Meet 1.3.1 Understanding 1.3.1 Specifically: F43: Failure of Success Criterion 1.3.1 due to using structural markup in a way that does not represent relationships in the content
6.5: Ensure that dynamic content is accessible or provide an alternative presentation or page. [Priority 2]	Conformance Requirement 1: Conformance Level: One of the following levels of conformance is met in full. Understanding Conformance Requirement 1 Level A: For Level A conformance (the minimum level of conformance), the Web page satisfies all the Level A Success Criteria, or a conforming alternate version is provided. Level AA: For Level AA conformance, the Web page satisfies all the Level A and Level AA Success Criteria, or a Level AA conforming alternate version is provided. Level AAA: For Level AAA conformance, the Web page satisfies all the Level A, Level AA and Level AAA Success Criteria, or a Level AAA conforming alternate version is provided. Note 1: Although conformance can only be achieved at the stated levels, authors are encouraged to satisfy and report progress toward meeting success criteria from all levels beyond the achieved level of conformance. Note 2: It is not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA Success Criteria for some content. Conformance Requirement 4: Accessibility-Supported Technologies Only: Only accessibility supported technologies are relied upon to satisfy the success criteria. Any information or functionality that is implemented in technologies that are not accessibility supported are also be available via technologies that are accessibility supported. (See Understanding accessibility support.) Understanding Conformance Requirement 4
7.2: Until user agents allow users to control blinking, avoid causing content to blink (i.e., change presentation at a regular rate, such as turning on and off). [Priority 2]	2.2.2 Pause, Stop, Hide: For moving, blinking, scrolling, or auto-updating information, all of the following are true: (Level A) How to Meet 2.2.2 Understanding 2.2.2 Moving, blinking, scrolling: For any moving, blinking or scrolling information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it unless the movement, blinking, or scrolling is part of an activity where it is essential; and Auto-updating: For any auto-updating information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it or to control the frequency of the update unless the auto-updating is part of an activity where it is essential. Note 1: For requirements related to flickering or flashing content, refer to Guideline 2.3. Note 2: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference. Note 3: Content that is updated from a process, real-time or remote stream is not required to preserve or present information that is generated or received between the initiation of the pause and resuming presentation, as this may not be technically possible, and in many situations could be misleading to do so. Note 4: An animation that occurs as part of a preload phase or similar situation can be considered essential if interaction cannot occur during that phase for all users, and if not indicating progress could confuse users or cause them to think that content was frozen or broken.
7.4: Until user agents provide the ability to stop the refresh, do not create periodically auto-refreshing pages. [Priority 2]	2.2.1 Timing Adjustable: For each time limit that is set by the content, at least one of the following is true: (Level A) How to Meet 2.2.1 Understanding 2.2.1 Turn off: The user is allowed to turn off the time limit before encountering it; or Adjust: The user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or Extend: The user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "press the space bar"), and the user is allowed to extend the time limit at least ten times; or Real-time Exception: the time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible; or Essential Exception: The time limit is essential and extending it would invalidate the activity; or 20 Hour Exception: The time limit is longer than 20 hours. Note: This success criterion acts to ensure that changes in content or context as a result of a time limit will not occur unexpectedly, which could prevent users from completing tasks. While exceptions to Success Criterion 2.2.1 where timing is essential exist, guideline 2.2 in general limits changes in content to those places where there is no other option. This success criterion should be considered in conjunction with Success Criterion 3.2.1 which puts limits on changes of content or context as a result of user action. 2.2.4 Interruptions: Interruptions can be postponed or suppressed by the user, except interruptions involving an emergency. (Level AAA) How to Meet 2.2.4 Understanding 2.2.4 3.2.5 Change on Request: Changes of context are initiated only by user request or a mechanism is available to turn off such changes. (Level AAA) How to Meet 3.2.5 Understanding 3.2.5 Specifically: G76: Providing a mechanism to request an update of the content instead of updating automatically
7.5: Until user agents provide the ability to stop auto-redirect, do not use markup to redirect pages automatically. Instead, configure the server to perform redirects. [Priority 2]	2.2.1 Timing Adjustable: For each time limit that is set by the content, at least one of the following is true: (Level A) How to Meet 2.2.1 Understanding 2.2.1 Turn off: The user is allowed to turn off the time limit before encountering it; or Adjust: The user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or Extend: The user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "press the space bar"), and the user is allowed to extend the time limit at least ten times; or Real-time Exception: the time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible; or Essential Exception: The time limit is essential and extending it would invalidate the activity; or 20 Hour Exception: The time limit is longer than 20 hours. Note: This success criterion acts to ensure that changes in content or context as a result of a time limit will not occur unexpectedly, which could prevent users from completing tasks. While exceptions to Success Criterion 2.2.1 where timing is essential exist, guideline 2.2 in general limits changes in content to those places where there is no other option. This success criterion should be considered in conjunction with Success Criterion 3.2.1 which puts limits on changes of content or context as a result of user action. 3.2.5 Change on Request: Changes of context are initiated only by user request or a mechanism is available to turn off such changes. (Level AAA) How to Meet 3.2.5 Understanding 3.2.5 Specifically: SVR1: Implementing automatic redirects on the server side instead of on the client side G110: Using an instant client-side redirect
10.1: Until user agents allow users to turn off spawned windows, do not cause pop-ups or other windows to appear and do not change the current window without informing the user. [Priority 2]	3.2.1 On Focus: When any component receives focus, it does not initiate a change of context. (Level A) How to Meet 3.2.1 Understanding 3.2.1 3.2.2 On Input: Changing the setting of any user interface component does not automatically cause a change of context unless the user has been advised of the behavior before using the component. (Level A) How to Meet 3.2.2 Understanding 3.2.2 3.2.5 Change on Request: Changes of context are initiated only by user request or a mechanism is available to turn off such changes. (Level AAA) How to Meet 3.2.5 Understanding 3.2.5 Specifically: H83: Using the target attribute to open a new window on user request and indicating this in link text SCR24: Using progressive enhancement to open new windows on user request
11.1: Use W3C technologies when they are available and appropriate for a task and use the latest versions when supported. [Priority 2]	No longer required for conformance to WCAG 2.0, but relates to "accessibility supported" technologies. Refer to Understanding Accessibility Support for more information.
11.2: Avoid deprecated features of W3C technologies.	No longer required for conformance to WCAG 2.0. [Priority 2]
12.3: Divide large blocks of information into more manageable groups where natural and appropriate. [Priority 2]	2.4.10 Section Headings: Section headings are used to organize the content. (Level AAA) How to Meet 2.4.10 Understanding 2.4.10 Note 1: "Heading" is used in its general sense and includes titles and other ways to add a heading to different types of content. Note 2: This success criterion covers sections within writing, not user interface components. User Interface components are covered under Success Criterion 4.1.2.
13.2: Provide metadata to add semantic information to pages and sites.	This is no longer required for conformance, but metadata can be used in a variety of ways to support WCAG 2.0. For more information, refer to Understanding Metadata.
13.3: Provide information about the general layout of a site (e.g., a site map or table of contents). [Priority 2]	2.4.5 Multiple Ways: More than one way is available to locate a Web page within a set of Web pages except where the Web Page is the result of, or a step in, a process. (Level AA) How to Meet 2.4.5 Understanding 2.4.5 Additional Notes: This is a partial mapping. This also maps to G63: Providing a site map.
13.4: Use navigation mechanisms in a consistent manner. [Priority 2]	3.2.3 Consistent Navigation: Navigational mechanisms that are repeated on multiple Web pages within a set of Web pages occur in the same relative order each time they are repeated, unless a change is initiated by the user. (Level AA) How to Meet 3.2.3 Understanding 3.2.3 3.2.4 Consistent Identification: Components that have the same functionality within a set of Web pages are identified consistently. (Level AA) How to Meet 3.2.4 Understanding 3.2.4 2.4.10 Section Headings: Section headings are used to organize the content. (Level AAA) How to Meet 2.4.10 Understanding 2.4.10 Note 1: "Heading" is used in its general sense and includes titles and other ways to add a heading to different types of content. Note 2: This success criterion covers sections within writing, not user interface components. User Interface components are covered under Success Criterion 4.1.2.
And if you use tables (Priority 2)	WCAG 2.0
5.3: Do not use tables for layout unless the table makes sense when linearized. Otherwise, if the table does not make sense, provide an alternative equivalent (which may be a linearized version). [Priority 2]	1.3.2 Meaningful Sequence: When the sequence in which content is presented affects its meaning, a correct reading sequence can be programmatically determined. (Level A) How to Meet 1.3.2 Understanding 1.3.2
5.4: If a table is used for layout, do not use any structural markup for the purpose of visual formatting. [Priority 2]	1.3.1 Info and Relationships: Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A) How to Meet 1.3.1 Understanding 1.3.1 Specifically: F43: Failure of Success Criterion 1.3.1 due to using structural markup in a way that does not represent relationships in the content.
And if you use frames (Priority 2)	WCAG 2.0 Succes Criteria
12.2: Describe the purpose of frames and how frames relate to each other if it is not obvious by frame titles alone. [Priority 2]	This is no longer required for conformance (because the longdesc attribute type on the frame element type has not been supported and is not defined in XHTML 1.1, the Working Draft of XFrames, or the Working Draft of XHTML 2.0). The `longdesc` attribute is still present in the Frames Module defined in XHTML Modularization.
And if you use forms (Priority 2)	WCAG 2.0
10.2: Until user agents support explicit associations between labels and form controls, for all form controls with implicitly associated labels, ensure that the label is properly positioned. [Priority 2]	User agents now support explicit associations of labels with form controls, so the "until user agents" clause has been satisfied. This is therefore no longer a requirement under WCAG 2.0. "Positioning labels to maximize predictability of relationships (future link)" is listed as an advisory technique for Success Criterion 1.3.1 (Level A).
12.4: Associate labels explicitly with their controls. [Priority 2]	1.3.1 Info and Relationships: Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text. (Level A) How to Meet 1.3.1 Understanding 1.3.1 4.1.2 Name, Role, Value: For all user user interface components (including but not limited to: form elements, links and components generated by scripts), the name and role can be programmatically determined; states, properties, and values that can be set by the user can be programmatically set; and notification of changes to these items is available to user agents, including assistive technologies. (Level A) How to Meet 4.1.2 Understanding 4.1.2 Note: This success criterion is primarily for Web authors who develop or script their own user interface components. For example, standard HTML controls already meet this success criterion when used according to specification. Specifically: H44: Using label elements to associate text labels with form controls
And if you use applets and scripts (Priority 2)	WCAG 2.0
6.4: For scripts and applets, ensure that event handlers are input device-independent. [Priority 2]	2.1.1 Keyboard: All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints. (Level A) How to Meet 2.1.1 Understanding 2.1.1 Note 1: This exception relates to the underlying function, not the input technique. For example, if using handwriting to enter text, the input technique (handwriting) requires path dependent input but the underlying function (text input) does not. Note 2: This does not forbid and should not discourage providing mouse inpu

In General (Priority 2)

WCAG 2.0

2.2: Ensure that foreground and background color combinations provide sufficient contrast when viewed by someone having color deficits or when viewed on a black and white screen. [Priority 2 for images, Priority 3 for text].

1.4.3 Contrast (Minimum): The visual presentation of text and images of text has a contrast ratio of at least 5:1, except for the following: (Level AA) How to Meet 1.4.3 Understanding 1.4.3

Large Print: Large-scale text and images of large-scale text have a contrast ratio of at least 3:1;
Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are incidental text in an image, or that are not visible to anyone, have no minimum contrast requirement.
Logotypes: Text that is part of a logo or brand name has no minimum contrast requirement.

1.4.6 Contrast (Enhanced): The visual presentation of text and images of text has a contrast ratio of at least 7:1, except for the following: (Level AAA) How to Meet 1.4.6 Understanding 1.4.6

Large Print: Large-scale text and images of large-scale text have a contrast ratio of at least 5:1;
Incidental: Text or images of text that are part of an inactive user interface component, that are pure decoration, that are incidental text in an image, or that are not visible to anyone, have no minimum contrast requirement.
Logotypes: Text that is part of a logo or brand name has no minimum contrast requirement.

3.1: When an appropriate markup language exists, use markup rather than images to convey information. [Priority 2]

1.4.5 Images of Text: If the technologies being used can achieve the visual presentation, text is used to convey information rather than images of text except for the following: (Level AA) How to Meet 1.4.5 Understanding 1.4.5

Customizable: The image of text can be visually customized to the user's requirements;
Essential: A particular presentation of text is essential to the information being conveyed.

Note: Logotypes (text that is part of a logo or brand name) are considered essential.

1.4.9 Images of Text (No Exception): Images of text are only used for pure decoration or where a particular presentation of text is essential to the information being conveyed. (Level AAA) How to Meet 1.4.9 Understanding 1.4.9

Note: Logotypes (text that is part of a logo or brand name) are considered essential.

3.2: Create documents that validate to published formal grammars. [Priority 2]

4.1.1 Parsing: In content implemented using markup languages, elements have complete start and end tags, elements are nested according to their specifications, elements do not contain duplicate attributes, and any IDs are unique, except where the specifications allow these features. (Level A) How to Meet 4.1.1 Understanding 4.1.1

Note: Start and end tags that are missing a critical character in their formation, such as a closing angle bracket or a mismatched attribute value quotation mark are not complete.

Additional Notes:

Validating to published formal grammars is a stronger requirement than what is required by Success Criterion 4.1.1 but validation is one of the sufficient techniques for this Success Criterion. Refer to Understanding Success Criterion 4.1.1

3.3: Use style sheets to control layout and presentation. [Priority 2]

This checkpoint maps to several sufficient and advisory techniques related to Success Criterion 1.3.1 (Level A), Success Criterion 1.3.2 (Level A), Success Criterion 1.4.1 (Level A), Success Criterion 1.4.4 (Level AA), Success Criterion 1.4.5 (Level AA), Success Criterion 2.4.7 (Level AA), Success Criterion 1.4.8 (Level AAA), and Success Criterion 1.4.9 (Level AAA). There is no direct mapping.

3.4: Use relative rather than absolute units in markup language attribute values and style sheet property values. [Priority 2]

1.4.4 Resize text: Text (but not images of text) can be resized without assistive technology up to 200 percent without loss of content or functionality. (Level AA) How to Meet 1.4.4 Understanding 1.4.4

Additional Notes:

Some aspects of Success Criterion 1.4.8 (Level AAA) also relate to this checkpoint.

3.5 Use header elements to convey document structure and use them according to specification. [Priority 2]

2.4.10 Section Headings: Section headings are used to organize the content. (Level AAA) How to Meet 2.4.10 Understanding 2.4.10

Note 1: "Heading" is used in its general sense and includes titles and other ways to add a heading to different types of content.

Note 2: This success criterion covers sections within writing, not user interface components. User Interface components are covered under Success Criterion 4.1.2.

3.6: Mark up lists and list items properly. [Priority 2]

Specifically:

H48: Using ol, ul and dl for lists

3.7: Mark up quotations. Do not use quotation markup for formatting effects such as indentation. [Priority 2]

Specifically:

F43: Failure of Success Criterion 1.3.1 due to using structural markup in a way that does not represent relationships in the content

6.5: Ensure that dynamic content is accessible or provide an alternative presentation or page. [Priority 2]

Conformance Requirement 1: Conformance Level: One of the following levels of conformance is met in full. Understanding Conformance Requirement 1

Level A: For Level A conformance (the minimum level of conformance), the Web page satisfies all the Level A Success Criteria, or a conforming alternate version is provided.
Level AA: For Level AA conformance, the Web page satisfies all the Level A and Level AA Success Criteria, or a Level AA conforming alternate version is provided.
Level AAA: For Level AAA conformance, the Web page satisfies all the Level A, Level AA and Level AAA Success Criteria, or a Level AAA conforming alternate version is provided.

Note 2: It is not recommended that Level AAA conformance be required as a general policy for entire sites because it is not possible to satisfy all Level AAA Success Criteria for some content.

7.2: Until user agents allow users to control blinking, avoid causing content to blink (i.e., change presentation at a regular rate, such as turning on and off). [Priority 2]

2.2.2 Pause, Stop, Hide: For moving, blinking, scrolling, or auto-updating information, all of the following are true: (Level A) How to Meet 2.2.2 Understanding 2.2.2

Moving, blinking, scrolling: For any moving, blinking or scrolling information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it unless the movement, blinking, or scrolling is part of an activity where it is essential; and
Auto-updating: For any auto-updating information that (1) starts automatically, (2) lasts more than five seconds, and (3) is presented in parallel with other content, there is a mechanism for the user to pause, stop, or hide it or to control the frequency of the update unless the auto-updating is part of an activity where it is essential.

Note 1: For requirements related to flickering or flashing content, refer to Guideline 2.3.

Note 2: Since any content that does not meet this success criterion can interfere with a user's ability to use the whole page, all content on the Web page (whether it is used to meet other success criteria or not) must meet this success criterion. See Conformance Requirement 5: Non-Interference.

Note 3: Content that is updated from a process, real-time or remote stream is not required to preserve or present information that is generated or received between the initiation of the pause and resuming presentation, as this may not be technically possible, and in many situations could be misleading to do so.

Note 4: An animation that occurs as part of a preload phase or similar situation can be considered essential if interaction cannot occur during that phase for all users, and if not indicating progress could confuse users or cause them to think that content was frozen or broken.

7.4: Until user agents provide the ability to stop the refresh, do not create periodically auto-refreshing pages. [Priority 2]

2.2.1 Timing Adjustable: For each time limit that is set by the content, at least one of the following is true: (Level A) How to Meet 2.2.1 Understanding 2.2.1

Turn off: The user is allowed to turn off the time limit before encountering it; or
Adjust: The user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or
Extend: The user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "press the space bar"), and the user is allowed to extend the time limit at least ten times; or
Real-time Exception: the time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible; or
Essential Exception: The time limit is essential and extending it would invalidate the activity; or
20 Hour Exception: The time limit is longer than 20 hours.

Note: This success criterion acts to ensure that changes in content or context as a result of a time limit will not occur unexpectedly, which could prevent users from completing tasks. While exceptions to Success Criterion 2.2.1 where timing is essential exist, guideline 2.2 in general limits changes in content to those places where there is no other option. This success criterion should be considered in conjunction with Success Criterion 3.2.1 which puts limits on changes of content or context as a result of user action.

2.2.4 Interruptions: Interruptions can be postponed or suppressed by the user, except interruptions involving an emergency. (Level AAA) How to Meet 2.2.4 Understanding 2.2.4

3.2.5 Change on Request: Changes of context are initiated only by user request or a mechanism is available to turn off such changes. (Level AAA) How to Meet 3.2.5 Understanding 3.2.5

Specifically:

G76: Providing a mechanism to request an update of the content instead of updating automatically

7.5: Until user agents provide the ability to stop auto-redirect, do not use markup to redirect pages automatically. Instead, configure the server to perform redirects. [Priority 2]

2.2.1 Timing Adjustable: For each time limit that is set by the content, at least one of the following is true: (Level A) How to Meet 2.2.1 Understanding 2.2.1

Turn off: The user is allowed to turn off the time limit before encountering it; or
Adjust: The user is allowed to adjust the time limit before encountering it over a wide range that is at least ten times the length of the default setting; or
Extend: The user is warned before time expires and given at least 20 seconds to extend the time limit with a simple action (for example, "press the space bar"), and the user is allowed to extend the time limit at least ten times; or
Real-time Exception: the time limit is a required part of a real-time event (for example, an auction), and no alternative to the time limit is possible; or
Essential Exception: The time limit is essential and extending it would invalidate the activity; or
20 Hour Exception: The time limit is longer than 20 hours.

3.2.5 Change on Request: Changes of context are initiated only by user request or a mechanism is available to turn off such changes. (Level AAA) How to Meet 3.2.5 Understanding 3.2.5

Specifically:

10.1: Until user agents allow users to turn off spawned windows, do not cause pop-ups or other windows to appear and do not change the current window without informing the user. [Priority 2]

3.2.1 On Focus: When any component receives focus, it does not initiate a change of context. (Level A) How to Meet 3.2.1 Understanding 3.2.1

3.2.2 On Input: Changing the setting of any user interface component does not automatically cause a change of context unless the user has been advised of the behavior before using the component. (Level A) How to Meet 3.2.2 Understanding 3.2.2

3.2.5 Change on Request: Changes of context are initiated only by user request or a mechanism is available to turn off such changes. (Level AAA) How to Meet 3.2.5 Understanding 3.2.5

Specifically:

11.1: Use W3C technologies when they are available and appropriate for a task and use the latest versions when supported. [Priority 2]

No longer required for conformance to WCAG 2.0, but relates to "accessibility supported" technologies. Refer to Understanding Accessibility Support for more information.

11.2: Avoid deprecated features of W3C technologies.

No longer required for conformance to WCAG 2.0. [Priority 2]

12.3: Divide large blocks of information into more manageable groups where natural and appropriate. [Priority 2]

2.4.10 Section Headings: Section headings are used to organize the content. (Level AAA) How to Meet 2.4.10 Understanding 2.4.10

Note 1: "Heading" is used in its general sense and includes titles and other ways to add a heading to different types of content.

Note 2: This success criterion covers sections within writing, not user interface components. User Interface components are covered under Success Criterion 4.1.2.

13.2: Provide metadata to add semantic information to pages and sites.

This is no longer required for conformance, but metadata can be used in a variety of ways to support WCAG 2.0. For more information, refer to Understanding Metadata.

13.3: Provide information about the general layout of a site (e.g., a site map or table of contents). [Priority 2]

2.4.5 Multiple Ways: More than one way is available to locate a Web page within a set of Web pages except where the Web Page is the result of, or a step in, a process. (Level AA) How to Meet 2.4.5 Understanding 2.4.5

Additional Notes:

This is a partial mapping.
This also maps to G63: Providing a site map.

13.4: Use navigation mechanisms in a consistent manner. [Priority 2]

3.2.3 Consistent Navigation: Navigational mechanisms that are repeated on multiple Web pages within a set of Web pages occur in the same relative order each time they are repeated, unless a change is initiated by the user. (Level AA) How to Meet 3.2.3 Understanding 3.2.3

3.2.4 Consistent Identification: Components that have the same functionality within a set of Web pages are identified consistently. (Level AA) How to Meet 3.2.4 Understanding 3.2.4

2.4.10 Section Headings: Section headings are used to organize the content. (Level AAA) How to Meet 2.4.10 Understanding 2.4.10

Note 1: "Heading" is used in its general sense and includes titles and other ways to add a heading to different types of content.

Note 2: This success criterion covers sections within writing, not user interface components. User Interface components are covered under Success Criterion 4.1.2.

And if you use tables (Priority 2)

WCAG 2.0

5.3: Do not use tables for layout unless the table makes sense when linearized. Otherwise, if the table does not make sense, provide an alternative equivalent (which may be a linearized version). [Priority 2]

1.3.2 Meaningful Sequence: When the sequence in which content is presented affects its meaning, a correct reading sequence can be programmatically determined. (Level A) How to Meet 1.3.2 Understanding 1.3.2

5.4: If a table is used for layout, do not use any structural markup for the purpose of visual formatting. [Priority 2]

Specifically: F43: Failure of Success Criterion 1.3.1 due to using structural markup in a way that does not represent relationships in the content.

And if you use frames (Priority 2)

WCAG 2.0 Succes Criteria

12.2: Describe the purpose of frames and how frames relate to each other if it is not obvious by frame titles alone. [Priority 2]

This is no longer required for conformance (because the longdesc attribute type on the frame element type has not been supported and is not defined in XHTML 1.1, the Working Draft of XFrames, or the Working Draft of XHTML 2.0). The longdesc attribute is still present in the Frames Module defined in XHTML Modularization.

And if you use forms (Priority 2)

WCAG 2.0

10.2: Until user agents support explicit associations between labels and form controls, for all form controls with implicitly associated labels, ensure that the label is properly positioned. [Priority 2]

User agents now support explicit associations of labels with form controls, so the "until user agents" clause has been satisfied. This is therefore no longer a requirement under WCAG 2.0.

"Positioning labels to maximize predictability of relationships (future link)" is listed as an advisory technique for Success Criterion 1.3.1 (Level A).

12.4: Associate labels explicitly with their controls. [Priority 2]

Specifically:

H44: Using label elements to associate text labels with form controls

And if you use applets and scripts (Priority 2)

WCAG 2.0

6.4: For scripts and applets, ensure that event handlers are input device-independent. [Priority 2]

Note 2: This does not forbid and should not discourage providing mouse inpu

[DRAFT] Comparison of WCAG 1.0 Checkpoints to WCAG 2.0, Grouped by Priorities

Page Contents

New WCAG 2.0 requirements not mentioned in the comparison tables below

New Level A requirements

New Level AA requirements

New Level AAA requirements

WCAG 1.0 Priority 1 checkpoints

WCAG 1.0 Priority 2 checkpoints